I'm purchasing a used enlarging lens and would like to know any benefits of the 4.0 over the 5.6 Rodenstock enlarging lenses ?
Thanks for any input !
GP

Why not tells us more about what you wish to accomplish.

What focal length are you looking at? Is the f4.0 an APO? If you are doing B&W I don't think the higher price of the APO will buy you anything over the non-APO. There may be some benefit of the APO for very large color printing. Again - we can be more helpful if we know what your main printing intentions are.

Bob

Besides from the obvious difference of one f stop, that one stop can make a big difference during your printing "routine." I find most lenses are sharpest stopped down 2 to 3 stops. With the F4 that would be F8 or F11, a one stop advantage when determining exposure times. The minimum I use is 2 stops for flatness of field. Also, I think the F4 is a six element. I use the APO only when going 20x24.
Good luck.

Sorry ...I had forgotten to write that the lens is an 80mm for 6x6 format . . Also, that I don't plan to enlarge any prints larger than @ 12x12" in B&W.

GP

Sorry ...I had forgotten to write that the lens is an 80mm for 6x6 format . . Also, that I don't plan to enlarge any prints larger than @ 12x12" in B&W.

GP
For that application I doubt that you will see any benefit from the f4; so go with the f5.6.

This Dave agrees with that Dave! :p